Ig VH, DH, and JH germ-line gene segments linked by overlapping cosmid clones of rabbit DNA.

Overlapping cosmid clones of rabbit germ-line DNA containing VH, DH and JH gene segments were isolated. The map of this cluster of cosmid clones indicated that the rabbit VH and JH regions were separated by 63 kb. Hybridization of Southern blots of these cosmid clones with two different DH segment probes identified a total of six DH segments within the region between the VH and JH regions. The nucleotide sequences of the JH region and one of the DH segments have been determined. The DH segment has conserved heptamer and nonamer sequences separated by 12 and 11 bp at the 3' and 5' sides, respectively, of the coding region and hence, appears to be a functional gene. The nucleotide sequence of the JH region revealed four functional JH gene segments and one JH pseudogene. Inasmuch as the JH region had previously been linked by contiguous overlapping clones with C mu, C gamma, C epsilon, and one C alpha gene, this VH-DH-JH cluster and the clones containing the Ig H chain C region genes represent 190 kb of contiguous germ-line DNA of the Ig H chain locus.